This invention relates generally to the field of aeronautics and more particularly to retarding and restraining devices utilizing cable or net supports.
Barricades or nets are normally used as emergency devices for retarding the motion of a vehicle in a limited amount of space. Present emergency barricades for arresting the motion of a landing aircraft generally consist of expendable webbing assemblies which are stretched across a runway in the path of the vehicle and include some form of nylon straps or ropes interconnected in various configurations and attached to an energy absorbing device. The aforesaid webbing generally comprises the barricade vertical members which engage the aircraft wings to equalize loading and absorb the force of the vehicle's forward motion. Present operational aircraft for which arresting barricades are designed range to maximum weights of 50,000 pounds, lengths of 78 feet, canopy heights of 121/2 feet, and wing spans of 78 feet (Navy A3 Skywarrior). In the past, normal loads imposed by current operational aircraft have cut, shredded and torn the vertical straps and loading members of the barricade due to the violent impact of aircraft engagement. Several possible deleterious effects of such strap failure during an arrestment include uneven loading on the vehicle causing violent motion of the vehicle and uneven deceleration with possible harm to the vehicle's occupants. These problems become more acute as the size and weight of the vehicle are increased. Presently, a space shuttle orbiter contemplated by NASA for travel between earth and an orbiting space station is of a size and weight magnitude considerably greater than any present operational aircraft capable of being arrested by current barricades. For example, the presently contemplated orbiter will weigh as much as 220,000 pounds, with an overall length of 125 feet, a canopy height of 30 feet, and a wing span of 96 feet. Problems of cutting, tearing and shredding are therefore greatly magnified, necessitating greater strength and resistance to cutting, shredding and abrasion. Mere increase of the size of current barricade components to meet the added strength requirements is not feasible because of the greatly increased bulk that would be produced. The added bulk would materially increase handling and rigging problems associated with such a barricade. In addition, the present problems of cutting, tearing and shredding of barricade members would not be alleviated. An additional problem is also encountered when connecting hardware on present barricades impact against the vehicle surface during engagement, causing considerable amounts of damage.